Source: http://io9.com/the-real-story-of-apollo-...

By 1966, the space race peaked: NASA received its highest budget ever, at just under 4.5% of the total US federal budget, at $5.933 billion dollars (around $43 billion today.) The United States had made clear gains in space by this point: Project Gemini had completed its final mission, and with efforts towards the next phase under Apollo were well under way. By this point, the social and political infrastructure and support for space had begun to wane, and would ultimately fall away after Apollo 11 successfully landed on the Moon's surface in July of 1969. After this point, NASA continued with planned missions, and eventually landed five additional Apollo missions on the Moon. (Another, Apollo 13, was unable to land after mechanical problems).

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Other major concerns have redirected US attentions from spaceflight: the United States' War on Terror, which is expected to cost US taxpayers over $5 trillion dollars in the long run.